Objectives: To investigate the association between amisulpride-induced hyperprolactinemia and the Taq1A polymorphism in the dopamine receptor D2(DRD2) gene in schizophrenic patients Methods: The plasma concentrations of prolactin were measured before and after treatment with amisulpride in one hundred and twenty-five schizophrenic patients. The effect of the Taq1A variants of the DRD2 gene on the risk of amisulpride-induced hyperprolactinemia was main the outcome measure. The genotyping for Taq1A(rs1800497) was performed using TaqMan single nucleotide polymorphism(SNP) genotyping assay. Results: There was a significant difference between baseline prolactin level and prolactin level at 6 weeks of treatment with amisulpride. But no correlations were found between ΔProlactin(prolactin level at 6 weeks minus the baseline prolactin level) and the Taq1A genotypes. Conclusion: This is the first study to investigate the association between the Taq1A polymorphism and the amisulpride-induced hyperprolactinemia in Korean schizophrenic patients. Futher large-scale researchs on various SNPs in the DRD2 gene will establish clear goals and provide for the unanswered questions described in this study.